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Motor examination of the lower limb essay

Milligan, MD; Tamara B. Primary sensory modalities include pain, temperature, light touch, vibration, and joint position sense. Sensation of the face is discussed in the videos Cranial Nerves Exam I and II, as are the special senses of smell, vision, taste, and hearing.

The spinothalamic tract mediates pain and temperature information from skin to thalamus. The spinothalamic fibers decussate cross over 1-2 spinal nerve segments above the point of entry, then travel up to the brainstem until they synapse on various nuclei in thalamus.

From the thalamus, information is then relayed to the cortical areas such as the postcentral gyrus also known as the primary somatosensory cortex.

Afferent fibers transmitting vibration and proprioception travel up to medulla in the ipsilateral posterior columns as fasciculus gracilis and fasciculus cuneatus, which carry information from the lower limbs and upper limbs, respectively. Subsequently, the afferent projections cross over and ascend to the thalamus, and from there to the primary somatosensory cortex. The pattern of a sensory loss can help to localize the lesion and determine the diagnosis. For example, testing the primary modalities allows the examiner to distinguish between a length-dependent peripheral neuropathy e.

In order to localize the sensory deficit, knowledge of neuroanatomy and the peripheral nervous system is crucial.

Motor examination of the lower limb essay

When seeing a patient with a peripheral sensory deficit, it can be helpful to think about what nerve root s may be involved. A spinal nerve root arises from every spinal segment and consists of both a sensory dorsal root and a motor ventral root, which provide innervation to a specific dermatome and myotome, respectively.

There are 31 paired spinal nerve roots: For example, the C5 through T1 roots form a network called the brachial plexus that controls movement and sensation in the upper limbs, including the shoulder, arm, forearm, and hand.

The brachial plexus gives rise to the radial, median, and ulnar nerves. The median nerve carries sensation from all fingers except the fifth finger and half of the fourth, which are carried by the ulnar nerve.

These nerve territories extend proximally on the palmar side of the hand. The ulnar and radial nerves carry sensory information from the dorsal side of the hands. In the lower extremities, T12-L4 form the lumbar plexus, and L4-S4 form the sacral plexus.

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These plexi give rise to peripheral nerves. A few of these peripheral nerves are the femoral, obturator, and sciatic nerves motor and sensory and the lateral femoral cutaneous nerve sensory only.

The sciatic nerve gives rise to the tibial and common peroneal nerves. Use of a dermatomal and peripheral nerve map can be helpful in localizing sensory dysfunction in both the upper and lower extremities. If primary sensory modalities are normal, cortical sensation or higher order aspects of sensation can be tested as well.

Cortical sensation is tested when there is reason to suspect a disorder of the brain. Cortical sensory testing can assist with localization of nervous system disorders. The cortical sensory examination includes tests for tactile localization extinctionstereognosis, graphesthesia, two-point discrimination, and point localization. Cortical sensory testing is not motor examination of the lower limb essay done during a screening neurological examination.

Procedure In a screening sensory examination, light touch, pain, and vibration are tested in the feet. The sensory examination is expanded in a patient with a complaint referable to the nervous system, or if other components of the examination are abnormal. Primary sensory testing Begin primary sensory testing by asking the patient if there is any change in sensation in the body. The patient can describe and demarcate the sensory changes to aid in the evaluation.

Light touch Using the tip of your finger or a piece of cotton, touch rather than stroke the patient's skin. Ask the patient to close eyes and tell you when the touch is felt.

  • For example, a broken leg that has recently been liberated from a cast will appear markedly atrophic;
  • Some areas, like the thigh, leg, arm and forearm, may be better evaluated by measurement;
  • This is not routinely done during a screening neurological exam;
  • For further information see Chapter 12.

Pain Explain that you will be touching the patient with either the sharp or dull end of a safety pin, but it should not hurt. With the patient's eyes closed, touch the hand, thumb and fingers with the sharp end of the pin but include a dull stimulus as well.

With each touch, ask the patient to determine if the stimulus is "dull" or "sharp. Repeat on the motor examination of the lower limb essay hand and arm, and compare between the sides. Repeat pinprick on the anterior side of the chest wall and compare the sides. Test the pain sensation in the lower extremities, beginning distally in the feet and comparing between symmetric areas on the two sides of the body and between the distal and the proximal areas. If an area of numbness is found on the patient, begin testing at the numb area and work outward.

Instruct the patient to say "yes" when feeling the normal pinprick sensation. Try to assess if there is a dermatomal pattern of sensory loss, which may be seen with a peripheral nerve injury. Temperature Use the tuning fork as a cold stimulus to test temperature sensation.

Tibial Nerve

Test tubes containing warm and cold water could be used as stimuli, but this is not usually done. Temperature sensation should replicate the findings found on the pain sensation examination.

Typically only one or the other is performed. Test the temperature sensation by touching the patient's skin with the tuning fork over the extremities in the same way the pain sensation is tested. Compare between the sides and between the proximal and distal areas of the same extremity.

Chapter 10 - Motor system examination

Vibration Use a low-pitched tuning fork of 128 Hz and strike the tines against the heel of your hand to produce a vibration. Place the stem of the tuning fork on the patient's great toe, Ask the patient to tell you when the vibration is no longer felt. Let the vibration fade until the patient no longer detects it, then apply the tuning fork to your own thumb to see if you still feel any vibration.

To make the vibration decrease faster, run your finger along the tines to dampen the vibration. If the patient cannot feel the vibration in the toes at all, repeat the test by placing the fork over the medial malleolus and, if not felt there, move the fork over the patella. Record the most distal level where the stimulus is felt. Compare the two sides.

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If there was decreased vibration appreciation found on examination of the lower extremities, test if the vibration can be appreciated in the fingers. Proprioception Hold the patient's large toe on the sides and demonstrate the test by moving the toe upward and downward while saying, "This is moving it up, and this is moving it down.

Repeat the same on the other side. If the patient cannot correctly identify movements of even large excursions, attempt to move the foot up and down around the ankle joint.

  • These small nylon fibers are designed such that the normal patient should be able to feel the ends when they are gently pressed against the soles of their feet;
  • Lower motor neuron damage results in decreased reflex and usually atrophy;
  • If primary sensory modalities are normal, cortical sensation or higher order aspects of sensation can be tested as well;
  • This is most commonly secondary to anxiety, but may occur with increased adrenaline such a pheochromocytoma or thyrotoxicosis;
  • Similarly, roots T12 to S4 form the lumbosacral plexus, which gives rise to the peripheral nerves;
  • It is clear that the direct projections in the corticospinal tract are responsible for highly skilled movements, especially of the hands.

Normally, people are able to identify even a few degrees of movement. If any indication of abnormality is present, test the position sense in the fingers at the metacarpophalangeal joints. Cortical sensation Tactile localization double simultaneous stimulation; extinction.

The Sciatic Nerve

With the patient's eyes closed, ask the patient to localize where you have touched. Initially, touch the side that you are concerned may have a deficit to confirm that sensation to light touch is intact. Then, simultaneously touch both sides and ask the patient to identify where and how many places were touched.

Touch the patient on one arm and then simultaneously on both arms.

Sensory Exam

Do the same with the legs. Extinction of the stimulus on one side may be a sign of a lesion in the contralateral parietal cortex. If there are suspected lesions of the sensory cortex, additional testing may be performed, including two-point discrimination, point localization, and looking for any asymmetry of optokinetic nystagmus.

Stereognosis tests the patient's ability to identify a common object e. Ask the patient to close the eyes and then identify the small object in the hand.

The patient may move the object around in the hand to feel it. Test the other hand in the same way. Importantly, the patient may not transfer the object from hand to hand. The patient should be able to identify it with one hand at a time. Patients should be able to differentiate coins, so it is not an acceptable answer to say "coin. Ask the patient to close the eyes. Use the blunt end of a pen to draw a large rendition of a number from 0-9 on the patient's palm.

Motor examination of the lower limb essay sure that the number is facing the patient and not you. Ask the patient to identify the number. Test the hand that you think is not affected first. Then, repeat on the other side.

Inability to correctly identify numbers may be indicative of a lesion in the contralateral parietal cortex. A complete sensory examination consists of testing primary sensory modalities as well as cortical sensory function.

  • This initial resistance gives way and then there is less resistance over the remaining range of motion clasp-knife phenomenon;
  • Motor function would also be affected see under motor exam;
  • Testing can be done with a paperclip, opened such that the ends are 5mm apart.

Primary sensory modalities include pain, temperature, light touch, vibration, and joint position sense, or proprioception. While cortical sensory testing examines the higher order aspects of sensation, like identifying an object only with the help of touch. The pattern of sensory loss detected during this exam can help in the diagnosis of conditions like peripheral neuropathy, radiculopathy or cortical lesions.

Here, we will first briefly review the two major sensory pathways, and discuss the peripheral sensory nerve distribution. Then, we'll demonstrate the steps involved in testing primary modalities and cortical sensory function assessment.

Let's begin by revisiting the anatomy of the sensory tracts. The two major sensory pathways are the posterior column-medial lemniscus pathway and the spinothalamic tract. These paths involve first order, second order and third order neurons. The information relayed between these neurons ultimately reaches the postcentral gyrus, also known as the primary somatosensory cortex, which is a prominent structure in the parietal lobe. The posterior column-medial lemniscus pathway is responsible for sensations like vibration, conscious proprioception, and discriminative, fine touch.

The first order afferent neurons of this pathway carry information from the mechanoreceptors and proprioceptors all the way up to the medulla oblongata. Here they synapse with the second order neurons, which decussate, or crossover, and travel to the thalamus.

From there, the third order neurons carry the information to the postcentral gyrus.